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The aid of learning management systems, widely spread among educational institutions, can enhance Project-Based Learning (PjBL) methodologies. Learning platforms allow self-learning and interaction with contents and materials anytime and anywhere using laptops and even mobile devices. This work explains a PjBL focused on engineering subjects conducted on a learning platform. In the frame of a "Motor and Generating Machines" course, 14 students analyzed an actual power plant run by biomass, in particular by dry olive pomace waste. The activities of the methodology are scheduled, presented, collected, and evaluated thanks to the learning platform. Through these activities, students learn and practice: power input and output estimation, biomass consumption, thermal efficiency, and power plant components. The activity includes an online test for student self-learning. The results from applying the PjBL methodology supported by a learning platform show that students easily understand the components of an actual thermal power plant and obtain most of the necessary energy parameters needed to manage the plant. However, exergy calculations are difficult for students since most of them did not correctly solve the questions related to this concept. [ABSTRACT FROM AUTHOR]

In this study, the solar Organic Rankine Cycle (ORC) system was analyzed to meet some of the electrical energy needed in large and medium-sized buildings and large enterprises such as hotels from solar energy. A simulation study was conducted for different districts in Türkiye that are rich in solar energy potential. These counties and the provinces they are affiliated with; Silifke-İçel, Alanya-Antalya, Bodrum-Muğla, Çeşme-İzmir. The power value transferred to the ORC was determined by considering the instantaneous radiation values and sunshine durations for the districts. The performance of solar ORC was determined by comparing fluids from three different organic fluid types. Organic fluids and types used in design; benzene-aromatic hydrocarbon, cyclohexane-alkane, octamethylcyclotetrasiloxane (D4)-siloxane. Considering the maximum electrical energy values obtained from Solar ORC in the summer months, it was seen that 205 MWh electricity generated was obtained for Silifke with benzene at a heat source temperature of 223 oC in July. Maximum solar parabolic trough collector (PTC) specific electric power value was determined as 59.52 W/m² in Alanya district with benzene in June. When the four districts are evaluated together, it has been determined that benzene performs better than cyclohexane by 3.8% on average and 23% better than D4. When the annual electrical energy values are examined, the highest production was determined as 1625 MWh with benzene fluid in Alanya district. [ABSTRACT FROM AUTHOR]

This study highlights the potential benefits of integrating Large Language Models (LLMs) into chemical engineering education. In this study, Chat-GPT, a user-friendly LLM, is used as a problem-solving tool. Chemical engineering education has traditionally focused on fundamental knowledge in the classroom with limited opportunities for hands-on problem-solving. To address this issue, our study proposes an LLMs-assisted problem-solving procedure. This approach promotes critical thinking, enhances problem-solving abilities, and facilitates a deeper understanding of core subjects. Furthermore, incorporating programming into chemical engineering education prepares students with vital Industry 4.0 skills for contemporary industrial practices. During our experimental lecture, we introduced a simple example of building a model to calculate steam turbine cycle efficiency, and assigned projects to students for exploring the possible use of LLMs in solving various aspect of chemical engineering problems. Although it received mixed feedback from students, it was found to be an accessible and practical tool for improving problem-solving efficiency. Analyzing the student projects, we identified five common difficulties and misconceptions and provided helpful suggestions for overcoming them. Our course has limitations regarding using advanced tools and addressing complex problems. We further provide two additional examples to better demonstrate how to integrate LLMs into core courses. We emphasize the importance of universities, professors, and students actively embracing and utilizing LLMs as tools for chemical engineering education. Students must develop critical thinking skills and a thorough understanding of the principles behind LLMs, taking responsibility for their use and creations. This study provides valuable insights for enhancing chemical engineering education's learning experience and outcomes by integrating LLMs. [Display omitted] • LLMs-assisted problem-solving procedure cultivate hands-on problem-solving and programming skills in ChemE education. • Student feedback on LLMs-assisted problem-solving procedure has been collected. • Suggestions to overcome misconceptions about integrating LLMs into ChemE education. • Provide examples and suggestions to aid integration of LLMs-assisted problem-solving procedure in ChemE education. • Recommendations for universities, ChemE professors, and students to adopt LLMs-assisted problem-solving procedure. [ABSTRACT FROM AUTHOR]

By establishing oxy-fuel combustion, direct water injection and waste heat recovery within conventional diesel engine, the compression ignition-internal combustion Rankine cycle (CI-ICRC) concept can be realized. It is capable of achieving ultra-high thermal efficiency and low emission. There have been studies on DWI timing in homogeneous charge compression ignition (HCCI) mode, but no systematic researches within CI-ICRC. Therefore, a prototype CI-ICRC engine is established in this work, the cycle performance (including in-cylinder pressure, heat release rate, brake thermal efficiency, etc.) and emission characteristics under different DWI timings are compared. The prototype engine was operated at 800 r/min. DWI temperature, pressure and duration are kept constant at 433 K, 35 MPa and 2 ms. The results indicate that DWI before combustion is more effective in reducing combustion intensity. The optimum DWI timing within this study is 320℃A, while the brake thermal efficiency (BTE) reaches the maximum of 46.6 % with a coefficient of variation close to 1 %. NOx and soot emissions are optimized but CO and HC emissions slightly increased with the utilization of DWI. The experimental results can provide guidance for future CI-ICRC engine optimization, and can also be utilized in providing reference information for DWI utilization within other novel internal combustion engine (ICE) concepts. [ABSTRACT FROM AUTHOR]

Experimental studies that investigate the utilization of ultra-low temperature (between 48 °C and 120 °C) waste heat, which forms 25 % of the global unrecovered waste heat, to drive thermal cooling systems are rare. Thus, this study fills a significant gap in the literature by (i) experimentally evaluating the performance of a new full-scale thermo-mechanical refrigeration (TMR) system at ultra-low temperatures ranging from 50 °C to 85 °C, (ii) characterizing its operation with different commercial refrigerants, and (iii) identifying optimal operating conditions and working fluids for the investigated TMR system. An organic Rankine cycle (ORC), vapor compression cycle (VCC), and expander-compressor unit (ECU) make up the TMR system. To ensure its efficient operation, flexibility, and reliability, a full-scale ECU-based TMR system with a design capacity of 1 kW at a heat source temperature of 85 °C is built and put through a series of tests. Furthermore, the TMR system is tested with different commercial refrigerants (R134a, R410A, R407C) over a wide range of operating conditions of the power loop. The results reveal that the ECU-based TMR system can work with ultra-low temperatures of 65 °C with an energy efficiency of 5.92 % and COP of 2.36, for the ORC and VCC, respectively. At a heat source temperature of 85 °C, a condenser water temperature of 15 °C, and an evaporator water temperature of 33 °C, the energy efficiency of the ORC and COP of the VCC are increased to 9.85 % and 3.99, respectively. For the cooling quality, the TMR system shows a minimum evaporator temperature of −10 °C using R134a in both the power and cooling loop, which is improved to lower than −20 °C by using R407C in the cooling loop. The results presented herein will be beneficial to the development, design, and optimization of refrigeration and power systems that utilize low-temperature waste heat. [ABSTRACT FROM AUTHOR]

Combined Cycle Power Plants (CCPP) are an important class of power generation technologies due to their efficiency (significantly higher than that of simple Rankine or Brayton cycles). The efficiency and reliability are the main factors that make the CCPP a tradeoff between standard Rankine/Brayton systems (highly reliable and predictable but with strong negative environmental impact) and renewables, such as photovoltaics, wind, etc. (high specific cost per MW, almost unpredictable, with low environmental impact). One of the issues of the CCPP technology is its dependence on the ambient parameters, especially inlet air temperature and humidity. The paper examines the importance of these factors and in its second part a case study is presented, attempting to develop a functional model to predict the power output of a CCPP system based on ambient parameters. [ABSTRACT FROM AUTHOR]

Combined Cycle Power Plants (CCPP) are an important class of power generation technologies due to their efficiency (significantly higher than that of simple Rankine or Brayton cycles). The efficiency and reliability are the main factors that make the CCPP a tradeoff between standard Rankine/Brayton systems (highly reliable and predictable but with strong negative environmental impact) and renewables, such as photovoltaics, wind, etc. (high specific cost per MW, almost unpredictable, with low environmental impact). One of the issues of the CCPP technology is its dependence on the ambient parameters, especially inlet air temperature and humidity. The paper examines the importance of these factors and in its second part a case study is presented, attempting to develop a functional model to predict the power output of a CCPP system based on ambient parameters. [ABSTRACT FROM AUTHOR]

A thermodynamic, economic and environmental analysis of a regasification system including a simple Organic Rankine Cycle (ORC) and an Open Organic Rankine Cycle (OC) to utilise the liquefied natural gas (LNG) cold energy is carried out in the present paper. The proposed system, called ORC-OC, uses ambient seawater as heat source (open loop) and is implemented on board a Floating Storage Regasification Unit (FSRU) in order to reduce the greenhouse gas (GHG) emissions associated with the electricity generation plant, i.e., dual fuel (DF) engines. Regarding the ORC working fluids analysed, an ethane/propane zeotropic mixture is applied. The ORC-OC is compared with the simple ORC architecture, giving the first one better energy (lower specific energy consumption), exergy (higher exergy efficiency) and environmental (lower CO2e emissions) results. When compared to the regasification systems installed on board, the ORC-OC system reduces the specific energy consumption by 86.99 % and increases the exergy efficiency by 17.82 % with respect to the most efficient conventional system installed on FSRUs (direct seawater regasification system), leading to a reduction of CO2e emissions of more than 80 %. In addition, the ORC-OC system is more costeffective than conventional regasification systems when the LNG price is above 6,508 USD/MMBtu. [ABSTRACT FROM AUTHOR]

In the present research, energy derived from the geothermal uid is utilized to generate power. In the first case of power generation, the model of the geothermal double-effect instantaneous evaporation cycle is employed, while in the second one, the single-effect evaporation combined cycle and Rankine cycle with different organic uids are utilized. The effect of several organic uids in the combined cycle is then examined. The SPECO method was then incorporated in the economic analysis. According to the mentioned analysis, net power generation reached its maximum value for the combined cycle with water vapor and its minimum value for the double-effect instantaneous evaporation cycle with a considerable difference. Throughout the experiments, increasing the separator pressure at the constant evaporator temperature reduced the power generation cost for combined cycles. The lowest power generation cost was attributed to the combined cycle with operating uid R113 while the highest amount of power generation cost was related to the combined cycle with ammonia uid. The exergoeconomic coeffcient, i.e., the ratio of the purchase price components to the sum of costs associated with total exergy destruction as well as the cost associated with purchasing cycle components, was also the highest in the combined cycle with R113 and the lowest in the double-effect instantaneous evaporation cycle. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the heat exchange component of the organic Rankine cycle (ORC) system, the evaporator directly affects the overall operation performance of the system. In this paper, an analytical method for energy level on the working fluid side of evaporator is proposed based on the energy level and enerty theory. The reliability, validity, and correlation of the proposed analytical method are studied by means of theoretical analysis, experimental evaluation, and Elman neural network (ElmanNN). The bilinear interpolation algorithm is used to analyze the non-linear relationship between the system parameters and the energy level on the working fluid side. In addition, the correlation between the heat exchange efficiency of the evaporator and the operating performance of the system is compared. Based on the back propagation neural network (BPNN), the high energy level area on working fluid side is accurately evaluated and verified, the direction and degree of the non-linear mapping relationship between the working fluid side energy level and the system performance are quantitatively evaluated, and the sensitivity of thermodynamic cycle parameters in the high energy level area on working fluid side is quantitatively evaluated. This study provides a novel approach to evaluate the operation of the evaporator in the ORC system. In addition, this study also provides guidance on how to keep the evaporator operating continuously in the high energy level area throughout the experiment. [ABSTRACT FROM AUTHOR]

An energy system affordable plan selection using renewable energy is a significant problem for designing and manufacturing these systems. The fault detection and thermoeconomic diagnosis in the combined solar Rankine cycle and multi-stage flash (MSF) desalination system is analyzed. In the suggested energy system, the linear parabolic solar collector is utilized as a heat source for the organic Rankine cycle, the domestic hot water, and the multi-stageflash desalination system. First, the energy balances and exergy analysis are implemented in the considered system, the energy value and exergy parameter are calculated. The exergy cost parameters are calculated for all parts and streams with the thermoeconomic and exergy cost accounting investigation. Finally, the thermoeconomic diagnosis is performed, and the malfunction of each component is evaluated, and the effect of each component's irreversibility on the other part is investigated. Results show that the linear parabolic solar collector has the maximum malfunction. Still, the condenser in the organic Rankine cycle is the most effective component on irreversibility increment among its counterparts. [ABSTRACT FROM AUTHOR]

Recently, renewable power plants utilize clean and sustainable resources for electricity generation. The Ocean Thermal Energy Conversion (OTEC) system uses ocean surface water as a high-temperature source and the water at a depth of the ocean as a low-temperature source. The difference between these temperatures is 20°C or greater, and the working uid with a low boiling point can be used for electricity generation. In a closed-cycle OTEC system, the working uid through a thermodynamic cycle based on the Rankine cycle can rotate the turbine and generate electricity. Due to the ocean surface temperature variation, the output power of the OTEC system changes and yields numerous states concerning the generated power of this plant. Thus, for integrating the OTEC systems with the power system, many aspects of power system including reliability may be affected and thus, new approaches must be developed for investigation of these effects. In this paper, the reliability of the power system containing the OTEC system based on the multi-state reliability model and the conditional value at risk concept is evaluated and the valuable indices used for generation expansion planning of the power system are calculated. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The atmosphere CLC is integrated with the combined sCO 2 -ORC for power generation. • The energy efficiency can reach 51.79% in the natural gas fired system. • The detailed technology and exergy analysis is conducted, and improvement strategies in off-design conditions are put forward. • The whole system performance is not sensitive to the CLC operating temperature, reducing the requirements for oxygen carriers and CLC reactors. Chemical looping combustion (CLC) has attracted wide interests with high-efficiency and near-zero energy penalty carbon capture. However, the low-pressure operation of the most adopted circulating fluidized-bed reactors restricts the application of the downstream combined (gas-steam turbines) cycle, leading to an unsatisfying system efficiency. For this reason, this paper integrates atmosphere CLC with the combined recompression supercritical CO 2 Brayton cycle and organic Rankine cycle (CLC-sCO 2 -ORC) for power generation. The proposed system was modeled and simulated with Aspen Plus to manifest its tech-economic feasibility. The sensitive analysis suggests that the optimal sCO 2 turbine inlet temperature and pressure are 700 °C and 280 bar, respectively, and the recompression split fraction is 0.72. Under the optimal condition, the energy efficiency of 51.79% is superior to the conventional natural gas combined cycle (NGCC) (49.38%) and other CLC-based power generation technology (50.13%). Exergy analysis was also performed to put forward some improvement strategies. Importantly, CLC operating temperature imposes nearly no impact on exergy loss. Besides, the economic indicator, levelized cost of electricity (LCOE) is supposed to be profitable at 79.17 $/MWh, which is lower than that of other CLC-based power generation system (83.12 $/MWh). [Display omitted] [ABSTRACT FROM AUTHOR]

A developing geothermal utilization is one of many Hungarian government efforts to generate electricity and heating applications from renewable energy sector, and to reduce fossil fuels usage due to the impact on the environment. Geothermal utilization for electricity generation has been implemented in Tura region and it is become the first geothermal plant in Hungary that producing electricity around 27 MW. The excess steam from Tura geothermal power-plant still has a potential energy that can converted to electricity and the objection in this study is implemented a heat recovery from excess steam through organic Rankine cycle (ORC) from the point of view energy and exergy analysis using different working fluids. The calculation result shows the Propane is produce the highest energy around 41 kW and the efficiency at 10.3%, while R125 produce the lowest energy around 10.25 kW and the efficiency at 8.17%. Moreover, based on the environmental analysis it is also found that R134a working fluid can be considered as environmentally and sustainability ORC's working fluid, compared to other working fluids, in this study. [ABSTRACT FROM AUTHOR]

This paper aims to review regasification technology installed in Floating Storage Regasification Units (FSRUs) and the potential offered by the exploitation of cold energy from liquefied natural gas (LNG) in these vessels. The assessment describes the main characteristics of regasification systems along with their respective advantages and limitations. Regasification systems in direct exchange (seawater and steam) and systems with intermediate fluids that use propane or water-glycol in the heat transfer process are studied. In recent years, water-glycol systems have cornered the market. The mixture, besides reducing the risk of freezing, is nonflammable, economical and highly available. Thermodynamic analysis of the regasification process shows that LNG cold energy is the main source of residual energy in these vessels; the specific energy and exergy content is more than double that of engine exhaust gases. Exploitation of this cold energy in power cycles could significantly reduce FSRUs harmful emissions and electrical energy could even be exported to shore. The organic Rankine cycle technology is the most well-known and widely studied, although scientific literature is scarce and there is a need to propose new regasification systems with cold energy exploitation that can be adopted on these vessels. [ABSTRACT FROM AUTHOR]

Power-to-gas (PtG) is a promising technology for the production of hydrogen via electrochemical reactions in water electrolyzers to manage intermittent power generation from renewable energy sources, such as wind and solar energy. Water electrolyzers generate hydrogen and highly purified oxygen as by-products. In this study, process analysis was performed on oxy-fuel combustion in a coal and biomass power plant and a PtG plant, which uses highly purified oxygen obtained from a water electrolyzer. The power-generation efficiency of an oxy-fuel power plant supplied with oxygen through an air separation unit and that of an oxy-fuel power plant supplied with oxygen in a polymer electrolyte membrane (PEM) water electrolysis process were also compared. Furthermore, we analyzed a combined system comprising an oxy-fuel power plant and PtG plant and found the resulting net power generation and power-generation efficiency to be higher than those of the individual oxy-fuel power plant that was supplied with oxygen through an air separation unit. This process efficiency was further improved when applying biomass to fuel the oxy-fuel combustion boiler rather than coal, and in cases where the steam-water is in a supercritical condition. Comparing with other methods, power generation using biomass is environment-friendly and sustainable. Finally, an economic analysis of hydrogen production showed that the levelized hydrogen cost was deduced to approximately $3.67/kg-H 2 , which is similar to the 2030 target value for hydrogen economy revitalization roadmap of the Korean government of 4000 KRW/kg-H 2. • Surplus oxygen utilized in the oxy-fuel boiler requires no separate air separation. • Oxy-fuel coal and biomass power plant combined with PtG plant had high net power generation. • Levelized H 2 cost of oxy-fuel plant with PtG plant was approx. $3.67/kg-H 2. • Facility capacity factor and electricity price were the main factors in the economic efficiency. • An increase in equipment capacity factor can increase the economic feasibility. [ABSTRACT FROM AUTHOR]

This paper aims to provide comprehensive 4E (energy, exergy, exergoeconomic, and exergoenvironmental) and advanced exergy analyses of the Refrigeration Cycle (RC) and Heat Recovery Refrigeration Cycle (HRRC) and comparison of the performance with R744 (CO2) and R744A (N2O) working fluids. Moreover, multi-objective optimization of the systems has been considered to define the optimal conditions and the best cycle from various perspectives. In HRRC, heat recovery is used as a heat source for an organic Rankine cycle. The energy and exergy analysis results show that utilizing HRRC with both refrigerants increases the coefficient of performance (COP) and exergy efficiency. COP and exergy efficiency for HRRC-R744 have been obtained 2.82 and 30.7%, respectively. Due to the better thermodynamic performance of HRRC, other analyses have been performed on this cycle. Exergoeconomic analysis results show that using R744A leads to an increase in the total product cost. Total product cost with R744 and R744A have been calculated by 1.56 $/h and 1.96$/h, respectively. Additionally, to obtain the processes' environmental impact, Life Cycle Assessment (LCA) is used. Exergoenvironmental analysis showed that using R744A increases the product environmental impact by 32%. Owning to the high amount of endogenous exergy destruction rate in the compressor and ejector compared to other equipment, they have more priority for improvement. Multi-objective optimization has been performed with exergy efficiency and total product cost objective functions as well as COP and product environmental impact for both refrigerants, which indicates that HRRC-R744 has better performance economically and environmentally. In optimal condition, the value of exergy efficiency, total product cost, COP, and the product environmental impact have been accounted for by 28.51%, 1.44 $/h, 2.76, and 149.01 mpts/h, respectively. [ABSTRACT FROM AUTHOR]

The application of the integrated solar-energy-based systems for water desalination and power production to some Iranian coastal regions has been investigated. For this purpose, the Integrated Multi Effect Desalination (MED) and Solar Rankine Cycle (SRC) are used. This work investigates the effects of the main thermodynamic parameters on the systems located at the southern Iranian cities of Chabahar, Qeshm, Kish and Asaluyeh. For each selected sites, the net power output of the system is 50 MWe. The results show that total exergy destruction is the highest for steam generator and cavity receiver which is in the range of 61% to 64% in several cases. Also, the Chabahar has the less total exergy destruction and the freshwater production is about 270.8 kg/s as most production. In addition, at other sites, the integrated cycle can produce about 266.2 kg/s of freshwater. Furthermore, the most total exergy destruction is related to Asaluyeh. [ABSTRACT FROM AUTHOR]

This paper aims to provide comprehensive 4E (energy, exergy, exergoeconomic, and exergoenvironmental) and advanced exergy analyses of the Refrigeration Cycle (RC) and Heat Recovery Refrigeration Cycle (HRRC) and comparison of the performance with R744 (CO2) and R744A (N2O) working fluids. Moreover, multi-objective optimization of the systems has been considered to define the optimal conditions and the best cycle from various perspectives. In HRRC, heat recovery is used as a heat source for an organic Rankine cycle. The energy and exergy analysis results show that utilizing HRRC with both refrigerants increases the coefficient of performance (COP) and exergy efficiency. COP and exergy efficiency for HRRC-R744 have been obtained 2.82 and 30.7%, respectively. Due to the better thermodynamic performance of HRRC, other analyses have been performed on this cycle. Exergoeconomic analysis results show that using R744A leads to an increase in the total product cost. Total product cost with R744 and R744A have been calculated by 1.56 $/h and 1.96$/h, respectively. Additionally, to obtain the processes' environmental impact, Life Cycle Assessment (LCA) is used. Exergoenvironmental analysis showed that using R744A increases the product environmental impact by 32%. Owning to the high amount of endogenous exergy destruction rate in the compressor and ejector compared to other equipment, they have more priority for improvement. Multi-objective optimization has been performed with exergy efficiency and total product cost objective functions as well as COP and product environmental impact for both refrigerants, which indicates that HRRC-R744 has better performance economically and environmentally. In optimal condition, the value of exergy efficiency, total product cost, COP, and the product environmental impact have been accounted for by 28.51%, 1.44 $/h, 2.76, and 149.01 mpts/h, respectively. [ABSTRACT FROM AUTHOR]

Concentrated Solar Power (CSP) technologies are now fast advancing and competitive. The improved performance (technical and economic) of solar thermal storage systems (STES) is a major contributor besides other breakthroughs in design of main components. The demand for small-scale, stand-alone CSP plants suitable for the distributed generation market is increasing. Therefore, this study aims to develop a cost-effective 10 MW-100% solar concentrated solar tower (CST) technology. Three simple power blocks are proposed and studied, including Open Gas Cycle (GC), Steam Rankine Cycle (SC) and Organic Rankine Cycle (OC), using ASPENHYSYS program to optimize the performance parameters. A thermal energy storage (TES) has been also studied using a developed MATLAB code. Solar field components have been selected and sized to deliver the input heat to the power blocks. Finally, a financial model has been developed by MATLAB to compute the Levelized Cost of Energy (LCOE). LCOE for the plant using SC as a power block is 0.0947 $/KWh which is lower than the GC and OC by 31.82% and 48.8%, respectively. Therefore, it is concluded a CST technology with packed rock bed TES and SC would be the appropriate choice for a stand-alone solar power plants capacities within range 10 MW. [ABSTRACT FROM AUTHOR]

This study analyzes a temperature condition that produces maximal power from a non-isothermal heat source under a finite number of heat-recovery thermodynamic cycles. Some previous studies have theoretically analyzed a system utilizing thermal energy from heat sources under multiple thermodynamic cycles assuming a constant heat-source temperature. However, many heat sources for heat-recovery thermodynamic cycles are non-isothermal, where the temperature changes considerably during heat exchange with the cycles. Therefore, it is necessary to consider the temperature change of the heat source. First, a condition that maximizes the power generated by a combination of single/multiple Carnot cycles from constant-specific-heat heat sources is analyzed, and the optimal temperature is derived analytically. Subsequently, simulations of the Rankine cycle and several patterns of the Kalina cycle are compared with those of the analytical model. These comparisons reveal that the proposed model effectively estimates the condition for heat-recovery cycles that produce maximal power from a non-isothermal heat source. Using the proposed method, the required number of cycles and their operating conditions under a given heat source condition are estimated, without any information about cycle configurations, types of working fluids, and iteration of simulation calculation under inappropriate conditions. In addition, a systematic exploration of the optimal system can be started from the proper initial condition. [ABSTRACT FROM AUTHOR]

• A novel geothermal system using a genetic algorithm based optimization is designed. • Using PEM and regenerative ORC with IHE, most of wasted energy is used. • Optimal points: exergy efficiency of 29.8 % and total product cost rate of 6 M$/year. • The combustion chamber and gasifier exhibit the highest exergy destruction. This study introduces an innovative approach by formulating and evaluating a synergistic biomass-geothermal structure, emphasizing optimized inter-component connections. The research stands out for its thorough analysis of parameter impacts on the system and variables, addressing an unexplored aspect in integrated energy systems. The multi-generation systems are the integration of a combined gasification gas turbine cycle, double flash geothermal cycle, and proton exchange membrane cycle for the generating power and hydrogen. The overall system and its subsystems are studied to explore how the performance of thermodynamics and the total cost rate are influenced by operating parameters. The best operational conditions for both subsystems and the overall system have been determined by analyzing the impact of operating parameters on the thermodynamic behavior and environmental impact through parametric studies. The findings indicate while Sabalan's current efficiency is 16.26 %, the system energy efficiency reached 24.89 % when coupled with other renewable source. To enhance the system's efficiency, a genetics algorithm was utilized to simultaneously optimize the total cost of exergy destruction and investment cost. The outcome of the multi-objective optimization revealed that the exergy efficiency of optimal point for the system is 29.8 % and a total investment cost is 6 (M$/year). [ABSTRACT FROM AUTHOR]

The gas turbine systems are some equipment; that have extensive industrial and military applications due to their unique characteristics. One of the major problems in association with utilization of gas turbines is the output power and thermal efficiency. One of the major methods that are used for increasing the power and thermal efficiency in this type of power systems is compressor's inlet air cooling. In this paper, the effect of fuel replacement for methane gasfired gas turbines with LNG and cooling the compressor's air inlet with the cold exergy of LNG fuel evaporation will be examined. In the first step, the energy balance equation is applied to the gas turbine with Methane and LNG fuel separately. Then the problem of fuel replacement in some mini and micro gas turbine has been examined and the appropriate engine with the most power and thermal efficiency is selected. In the next step, the exergetic analysis of considered systems is performed and exergetic parameters of the two systems are compared together. Finally, the advance exergy analysis is performed and effects of fuel replacement on exergetic cost parameter and environmental characteristics are evaluated. [ABSTRACT FROM AUTHOR]

In recent years, there have been increasing studies on topping cycles of combined cycle power plants with very high working temperature (about 3000 K). One of the thermal cycles, which have the ability to work in this temperature range, is MHD-Magneto hydrodynamic- cycle. MHD cycle can operate in two states. One state is the open cycle, and the other one is the close cycle. In both mentioned states there is a large amount of waste heat that can be recovered. It seems that the use of recovered heat from MHD cycles as the heat source for a gas turbine cycle namely Brayton according to their working temperature is promising. The objective of this study focused on energetic, exergetic, exergoeconomic and environmental (4E) analysis and evaluation of a proposed cycle based on the integration of combined cycle with MHD generator as the topping cycle. In this regard, the thermodynamic simulation of the plant has been performed. To verify of the thermodynamic simulation, the results have been compared with Thermoflex software and the data in the literature. In addition, exergetic, exergoeconomic, and environmental modeling and evaluation have been performed through computer code. The results show the good accuracy of the thermodynamic simulation for the integrated system. Also, the proposed cycle has a higher efficiency with the lower cost of exergy destruction and lower emission. [ABSTRACT FROM AUTHOR]

The increasing need of renewable energy sources leads to the study of different alternative power plants. One of them is the thermo-electrical conversion by solar concentration power plants with an open volumetric receiver, using nonpressurized air as the heat transfer fluid. Due to the poor heat transfer characteristics, a large air mass flowrate is needed in the solar tower to transfer a sufficient amount of heat to a conventional steam power cycle. The subject of this study is a solar-thermal plant with 100 MW electrical power output. The intermediate heat transfer fluid, air, circulates in a semi-open circuit, and 1.125 compression ratio is required by the forced convection circuit. The inherently high air temperatures and mass flowrate require the design of a compressor from scratch, which is the aim of this study. The design starts from the selection and the sizing of the compressor, based on the standard monodimensional turbomachinery theory, and continue with the verification of its fluid dynamic performance, based on a commercial CFD code (ANSYS-FLUENT). A 2D case is evaluated first, to ensure that the geometry is working correctly, and then the full 3D geometry is simulated to quantify the real performance of the compressor. A preliminary structural analysis of the blade is also performed to verify the structural integrity of the chosen configuration. [ABSTRACT FROM AUTHOR]

• A 300 MW oxy-fuel combustion plant with cryogenic air separation unit is assessed. • Supersonic shock wave compression was applied for CO 2 compression. • Organic Rankine cycle is used to recover wasted heats. • Thermal efficiency was improved about due to heat recovery. • Economic performance of coal-fired power plants (without and with ORCs) were evaluated and compared. Oxy-fuel combustion is currently most potential technology to reduce carbon dioxide emission from coal based power plants. This work describes thermo- economic analysis of CO 2 capture technology by assessment of detailed models of a 300 MW steam generation unit, an oxygen separation unit and shock wave CO 2 compression unit that are developed using Aspen HYSYS v9. The overall efficiency of the oxy-fuel combustion plant reduced by 10.98% due to implementation of air separation and CO 2 sequestration systems. To reduce the efficiency penalty, the waste heat released at different portions of plant is used to boost an organic Rankin cycle for power generation. CO 2 compression intercoolers and air separation unit coolers are two low grade heat sources which are utilized in ORCs. By recovering the wasted heats, the unit power consumption of oxygen production decreases from 227.3 to 214.2 kW h/t O 2 , power plant efficiency drop reduces about 1.51% and cost of electricity decreases from 67.03 to 64.94 €/MWh. The results indicate that proposed ORCs are thermodynamically and economically feasible to integrate with plant to increase the net efficiency. [ABSTRACT FROM AUTHOR]

• Waste heat recovery of both latent and sensible thermal energy in the ED system. • Simultaneous optimization helps balance bilateral interests of complex systems. • Retrofit the existing ED system with minor modification by implementing ORC. • Integration of economizer(s) can reuse self-heat to reach considerable benefit. • Maximum reusing inherent waste heat should be prior to recovering externally. The separation of close-boiling and azeotropic components by extractive distillation (ED) is a costly process. Because ED columns usually have relatively large top/bottom temperature difference, traditional energy-saving measures like heat integration/heat pump, are limited in reusing the system inherent waste heat. However, this opens an otherwise door for organic Rankine cycle (ORC), capable of converting waste heat into power regardless of the large temperature span. Consequently, several integrated ED-ORC systems with or without economizer(s) are therefore proposed, aiming at recovering both latent and sensible waste heat. An azeotropic n-heptane/isobutanol separation is used to illustrate the performance of these integrated systems. R227EA is selected as the ORC working fluid from 11 chlorine free candidates for the highest thermal efficiency of 8.23%. Compared to the basic case, the optimum integrated system without economizer only reduces TAC by 3.01%. While reusing the system inherent waste heat by adding economizer(s) can dramatically enhance the energy efficiency, leading to TAC saving up to 30.30%. The TAC reduction is attributed to dramatic hot utility consumption saving (∼ 45%). Sharing close technical parameters, the ED process will benefit more when retrofitted into the integrated systems under minimized column modifications. [ABSTRACT FROM AUTHOR]

• Steam extraction to the reboiler is optimized by inserting a butterfly valve in the IP-LP crossover downstream of the steam extraction point. • Steam throttling at reduced power plant loads maintains sufficient energy flow to the reboiler for continued capture operations at reduced loads. • Recovering flue gas waste heat for condensate preheating reduces output losses. • Increasing the operating temperature and pressure of the deaerator, maximizes the usage of waste heat for condensate preheating. • Configuring condensate preheaters in series with the low-pressure feed water heaters eases transitioning between capture and non-capture mode. Post-combustion CO 2 capture processes require thermal energy (from steam) for amine regeneration. In coal-fired power stations, steam can be extracted from within the steam cycle – resulting in a power production penalty. Heat integration is the study of minimizing energy consumption while maximizing heat recovery; required for successful CCS retrofits. In October 2014, the world's first fully integrated carbon capture facility, SaskPower's Boundary Dam Unit 3 (BD3), went on line. Various modifications to the turbine and feed heating system at BD3 contributed greatly to overall project costs. Novel heat integration strategies can reduce these costs. SaskPower's Shand Power Station (Shand) is a 305 MW, single unit, subcritical, lignite coal-fired power plant producing approximately 1100 kg of CO 2 /MWh. Shand's capacity is twice that of BD3's - an ideal candidate for a CCS scale-up project. Using the design of the BD3 facility as a basis, heat integration analysis of the existing steam cycle at Shand was conducted using GateCycle™with aims to minimize costly modifications to the feed heating system. A baseline model was built using Shand's heat balance and served as the design case. Configurations of steam extractions to the deaerator (DEA), extractions to the reboiler, and utilization of a flue gas cooler (FGC) working in conjunction with a condensate pre-heater (CPH) train were investigated. Optimization of steam extraction to the reboiler and a novel configuration of the condensate preheating train integrated within the LP feed heating system were also accomplished. [ABSTRACT FROM AUTHOR]

ORCs are widely recognized as one of the most suitable solution for energy recovery, if the temperature of the heat source is of about 200°C, or lower. In case of heat sources of about 100 kW or smaller, the more common solutions prescribe a simple cycle and a single stage expander, in order to reduce complexity and costs. Scroll expanders, derived from scroll compressors, are expected to be available at very low unit costs. The drawbacks of this kind of solutions, originally designed for automotive, or HVAC applications, are mainly two: the low fixed volumetric expansion ratio and the small volumetric flow rate, that are not always well-suited for the requirements of power production. In this paper, different ORCs with multiple expansions are evaluated with the aim of achieving a better exploitation of small scale-low temperature waste heat sources. The comparison takes in consideration different possible solutions for the multiple expansions, with internally recuperated and not-recuperated cycles, whilst the data describing the actual behaviour of compressors derived scroll expanders have been previously obtained by a test rig, set up at the University of Trieste, using R245fa as working fluid. [ABSTRACT FROM AUTHOR]

Abstract The solar energy driven Rankine cycle with CO 2 -H 2 O binary mixture as a working fluid driven by solar energy is proposed to increase the pressure ratio and specific work in this work. As compared with CO 2 working fluid, the condensing temperature increases with the increment of water fraction, and the working fluid with lower pressure is condensed into liquid at ambient temperature. As compared with supercritical CO 2 (S-CO 2) cycles, the pressure ratio of the proposed cycle is improved by reducing the outlet pressure of turbine, and the consumption work of compression is reduced by compressing the liquid working fluid. As a result, the specific work of the proposed cycle is higher than that of S-CO 2 cycle The characteristics of working fluid and parameters optimization are performed with different pressures and compositions of working fluid, and the energy and exergy balances at the design point are conducted to analyze the performances of the system. Theoretical results show that there is an optimal value of cycle efficiency when the mole fraction of water is increased. The solar-to-electric efficiency on the nominal condition reaches to 29.36%, which is higher than existing solar tower systems. Research findings introduce a promising approach for the efficient utilization of the abundant solar resources. [ABSTRACT FROM AUTHOR]

Traditional fossil fueled power plants are commonly based on steam Rankine cycle or Brayton Joule cycle. Using water or air as working fluid is obviously the most obvious choice for the wide availability of these substances in nature. However, the scarcity of natural energy sources and the strong need of reducing environmental impact have necessarily drawn the research to new energy systems configurations operating with other working fluids, which are able to recover lower temperature sources, such as Sun or industrial wasted heat. The variety of new working fluids (refrigerants or organic fluids) widens the choice to a variety of configurations that can be tailored to the specific source characteristics and boundary constraints. It is not always easy or even possible to conceive the best configuration for given specifications with the mere experience of a common designer. To design a new system configuration, the designer normally uses some "non-codified rules" deriving from his knowledge of basic thermodynamics and energy engineering. This paper aims instead at showing a practical tool that is based on a new methodology, named SYNTHSEP, to generate new energy system configurations. This methodology starts from the simple thermodynamic cycles operated by a given fluid made up of the four fundamental processes (compression, heating, expansion and cooling) and uses a rigorous set of codified rules to build the final system configuration. The paper presents the basics of the new methodology and how it has been implemented in a practical tool that simply requires the information about the elementary cycles and their shared processes as input data. [ABSTRACT FROM AUTHOR]

The gas turbine systems are some equipment; that have extensive industrial and military applications due to their unique characteristics. One of the major problems in association with utilization of gas turbines is the output power and thermal efficiency. One of the major methods that are used for increasing the power and thermal efficiency in this type of power systems is compressor's inlet air cooling. In this paper, the effect of fuel replacement for methane gasfired gas turbines with LNG and cooling the compressor's air inlet with the cold exergy of LNG fuel evaporation will be examined. In the first step, the energy balance equation is applied to the gas turbine with Methane and LNG fuel separately. Then the problem of fuel replacement in some mini and micro gas turbine has been examined and the appropriate engine with the most power and thermal efficiency is selected. In the next step, the exergetic analysis of considered systems is performed and exergetic parameters of the two systems are compared together. Finally, the advance exergy analysis is performed and effects of fuel replacement on exergetic cost parameter and environmental characteristics are evaluated. [ABSTRACT FROM AUTHOR]

The article attempts to clarify the meaning of internal and external irreversibility using the example of a heat engine. It has been proved that the efficiency of an internally reversible but externally irreversible engine is almost 50% of the efficiency of a totally reversible engine. [ABSTRACT FROM AUTHOR]

Carbon Capture, Utilization and Storage (CCUS) is a widely discussed method that can help reduce carbon emissions of energy intensive plants. The goal of this work is to evaluate from a techno-economic point of view such a plant that uses captured CO 2 and renewable H 2 obtained in a carbon-free way and produces methanol (MeOH). The paper presents (i) the impact of using a higher conversion rate (30%) than in previously reported works, (ii) the use of a gas turbine and (iii) the addition of organic Rankine cycles (ORC) for reducing the energy consumption. The CCUS plant uses 142.6*10 6  kg of CO 2 annually, reduces the amount of CO 2 emitted by 140*10 6  kg/year and produces 100*10 6  kg/year of MeOH. H 2 is obtained on site, using a water-electrolyzing unit; this consumes 130 MW e and generates the necessary H 2 for the process. The proposed MeOH production plant is designed and simulated in ChemCAD. Total purchased equipment cost and operational costs are estimated using the process flow modeling. Key performance indicators (KPI) are calculated using the mass and energy balances obtained. The calculated capital costs are similar to previously reported results in the literature. A rigorous mass and energy integration of the plant resulted in an energetically fully self-sufficient MeOH plant, not taking into account the water-hydrolyzing unit. Electricity price is the main contributor for operational costs, either this should be halved, MeOH prices should increase two times or CO 2 prices should increase to 0.255 €/kg to make the process economically viable. [ABSTRACT FROM AUTHOR]

A small vehicle-mounted, organic Rankine cycle (ORC) waste heat power generation system is built and optimized based on recovering expansion preheater after exhausting high temperature steam. Using the first and second law of thermodynamics, thermodynamic analysis, energy analysis and energy calculation of the small vehicle-mounted ORC waste heat power generation system were established. Taking R123 as working medium, heat source temperature 300℃, the thermal efficiency and total thermal efficiency of the system were calculated with given working medium flow and pressure. The total thermal efficiency of the system with/without preheater are 23.1% and 10.8% respectively. The heat transfer of the evaporator is 7.35kJ and 4.67kJ respectively. The results show that compared with the traditional ORC system without a preheater, the heat efficiency of the ORC system and the heat transfer coefficient of the evaporator are greatly improved. [ABSTRACT FROM AUTHOR]

There are a large quantity of low grade waste heat which is generally less than 90℃ in some industrial plants. How to efficiently utilize this part of heat during the nonheating season has become an interesting and significant research topic during the last decade. In this study, a simulation model of an organic rankine cycle (ORC) power generation system is developed. Using the waste water of a steel mill as the heat source of the ORC system, the most efficient available working medium named R245fa is found under the designed working condition. The influence of the temperature variation of the heat source on the performance of the entire system is also investigated in this paper. The result shows that the electric power output and the system thermal efficiency can be increased with the increase of the heat source temperature. According to the analysis of this investigation, when the heating temperature increases from 70 ℃ to 90 ℃, the electric power increases from 212KW to 805KW and the thermal efficiency increases from 2.14% to 7.76%. [ABSTRACT FROM AUTHOR]

Waste heat recovery of low-to-medium grade heat sources such as solar energy or biomass using Organic Rankine Cycle (ORC) technology has received growing attention recently. Few manufacturer of biomass (wood logs) stoves utilizes silicon-carbide as the material for manufacturing of their stoves to facilitate slow-heat-release for a long period of time for up to twelve hours. Despite good performance of these stoves, there is still significant amount of heat that is wasted through exhaust at the temperature of between 240 °C to 270 °C. This paper investigated various strategies to minimize heat losses to the environment by introducing an ORC system that can capture the waste heat and convert it into useful power. The stove’s temperature distribution as well as identification of potential location for the ORC evaporator were obtained using experimental testing. Such results were then employed for validation of a CFD model and it was shown that this CFD model can fairly accurately predict both temperature distribution and recovered heat on the ORC evaporator coils. Among investigated scenarios, “Modification 2” proved to be most effective as it not only preserved the heating functionality of the stove but also improved the stove’s efficiency by about 20% while generating 1.113 kW of electricity. [ABSTRACT FROM AUTHOR]

In this paper, an integrated power generation system of Kalina cycle system (KCS) and organic Rankine cycle (ORC) with LNG cold energy exploitation and CO 2 capture is introduced. The composite circulation system can fully recover and use the medium and low temperature waste heat to reduce the greenhouse gas emissions. To evaluate the system performances, the thermodynamics model was established and the system was simulated by using Aspen HYSYS software. Thermodynamic analysis has been performed to study the effects of turbine inlet temperature, NH 3 mass fraction, evaporation pressure and CO 2 capture pressure on the KCS/ORC integrated system. The optimal conditions were also investigated and identified. Exergy analysis of the components operated on KCS or ORC has also been demonstrated. The results showed that the optimal values of the network output, thermal efficiency and CO 2 captured quantity of the system were respectively 394.685 kW, 53.25% and 0.3 t/t CO2 (0.6 t/t LNG ), while the evaluation indexes of the power recovery efficiency and exergy efficiency were respectively 36% and 41.42%. The exergy loss efficiency of each component was examined. It was indicated that the whole system has significant advantages in waste heat recovery. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the thermodynamic performance of a novel small-scale power plant that employs a combined cycle for the energy generation from carbon-neutral biomass, such as pruning residues. The combined cycle is composed of an externally fired Joule Brayton cycle followed by a bottoming steam cycle. The topping cycle has the unique particularity of being composed of a cost-effective turbocharger taken from the automotive industry, in place of a more expensive commercial micro-turbine. The turbocharger can be either directly connected to the electric generator (after a few modifications) or coupled (without modifications) with a power turbine moving the generator. The use of solid biomass in the proposed plant is allowed by the presence of an external combustor and a gas-to-gas heat exchanger. The warm flue gases exhausted by the topping cycle are used in a bottoming cycle to produce steam, which can power a steam expander. This paper thermodynamically assesses the novel combined cycle in the configuration for the topping cycle that employs a turbocharger coupled with a power turbine capable of generating 30 kW of electrical power. Furthermore, the comparison between the performance obtained using the bottoming water Rankine cycle and a bottoming Organic Rankine Cycle is provided. [ABSTRACT FROM AUTHOR]

This paper focuses on the thermodynamic modelling and parametric optimization of an Organic Rankine Cycle (ORC) which recovers the heat stored in a thermal energy storage (TES). A TES with two molten-salt tanks (one cold and one hot) is selected since it is able to operate in the temperature range useful to recover heat from different sources such as exhaust gas of Externally Fired Gas Turbine (EFGT) or Concentrating Solar Power (CSP) plant, operating in a network for Distributed Generation (DG). The thermal storage facilitates a flexible operation of the power system operating in the network of DG, and in particular allows to compensate the energy fluctuations of heat and power demand, increase the capacity factor of the connected plants, increase the dispatchability of the renewable energy generated and potentially operate in load following mode. The selected ORC is a regenerative cycle with the adoption of a Heat Recovery Vapour Generator (HRVG) that recovers heat from molten salts flowing from the Hot Tank to the Cold Tank of the TES. By considering the properties of molten salt mixtures, a ternary mixture able to operate between 200 and 400 °C is selected. The main ORC parameters, namely the evaporating pressure/temperature and the evaporator/condenser pinch point temperature differences, are selected as variables for the thermodynamic ORC optimization. An automatic optimization procedure is set up by means of a genetic algorithm (GA) coupled with an in-house code for the ORC calculation. Firstly, a mono-objective optimization is carried out for two working fluids of interest (Toluene and R113) by maximization of the cycle thermal efficiency. Afterwards, a multi-objective optimization is carried out for the fluid with the best performance by means of a Non-dominated Sorting Genetic Algorithm (NSGA) in order to evaluate the cycle parameters which maximize the thermal efficiency and minimise the heat exchanger surface areas. Toluene results able to give the best trade-off between efficiency and heat exchanger dimensions for the present application, showing that by with respect to the best efficiency point, the heat exchange area can be reduced by 36% with only a penalty of 1% for the efficiency. [ABSTRACT FROM AUTHOR]

In this paper, superheated and saturated vapor ORCs commonly utilized as waste heat recovery systems of a marine power plant are investigated. First, a parametric study with different organic fluids has been carried out by applying conventional exergy and exergoeconomic analyses to the system considered in order to identify the best possible operating conditions and also to evaluate the findings of conventional exergy-based analyses. Then, advanced exergy and exergoeconomic analyses have been performed on ORCs by splitting exergy destruction rates, exergy destruction costs and investment costs of components and overall system to identify avoidable parts of costs and exergy destructions. Finally, decision criteria were suggested on the selection of more appropriate system depending on the results of the analysis. [ABSTRACT FROM AUTHOR]

The internal combustion engines are the most applied energy converters in the passenger cars. In order to increase their efficiency, energy integration techniques are used to recover the waste heat. An adapted methodology is required to design the Organic Rankine Cycle (ORC) as a waste heat recovery technology and to test the influence of the external temperature on its efficiency. The idea is to clusterize the external temperature profile on typical external temperature multi-periods. The energy system design is then tested on these typical multi-periods. In this article the methodology is applied on a vehicle with a small gasoline engine, in order to define the energy integrated configuration of the vehicle and to estimate the cost of the additional equipment. The performances indicators of the energy integration technology of the internal combustion engine is analysed and discussed, according to the multi-periods. The energy recovery potential of a single stage ORC for a small gasoline engine is assessed for different temperature profiles. The ORC equipment is simultaneously pre sized and its cost is estimated. The highest powertrain efficiency improvement due to the waste heat recovery for a small gasoline engine is estimated as 7%. [ABSTRACT FROM AUTHOR]

This paper aims at assessing the performance of a waste heat-to-power plant by means of an ORC (Organic Rankine Cycle) system coupled with two-phase closed thermosyphons (or gravity-assisted heat pipes or wickless heat pipes). The heat exchanger, made up of two-phase closed thermosyphons, is used for conveying heat from exhaust stream to ORC working fluid. In reality, a hot oil loop or a pressurized hot water loop or a saturated steam loop or even a direct evaporator is often used to transfer heat from the heat source to the ORC system. However, installing a heat exchanger directly in the hot gas paths of ORC system evokes the concerns for the flammability and/or toxicity of organic working fluids especially when the heat source has a relatively high temperature. Also the use of an intermediate heat carrier loop such as thermal oil or saturated steam or pressurized water loop is costly and involves installation of comparatively heavy components. In principle, the use of two-phase closed thermosyphons for capturing and transporting heat from a waste heat source to organic working fluid is less expensive than utilizing an intermediate heat transfer loop and eliminates safety issues as in the case of direct installation of an ORC evaporator in the hot gas paths. [ABSTRACT FROM AUTHOR]

In the authors' previous study, an axial force-flexural moment (P-M) interaction curve model was proposed to evaluate fire-resisting performances of reinforced concrete (RC) column members. The proposed method appeared to properly consider the axial and flexural strength degradations including the secondary moment effects in RC columns due to fire damage. However, the detailed P-M interaction curve model proposed in the authors' previous study requires somewhat complex computational procedures and iterative calculations, which makes it difficult to be used for practical design in its current form. Thus, the aim of this study was to develop a simplified P-M interaction curve model of RC columns exposed to fire considering the effects of fire damage on the material performances and magnitudes of secondary moments. The simplified P-M interaction model proposed in this study was verified using 66 column fire test results collected from literature, and the verification results showed that the proposed simplified method can provide an adequate analysis accuracy of the failure loads and fire-resisting times of the RC column specimens. [ABSTRACT FROM AUTHOR]

Abstract: The paper aims at analysing the energetic performances of Organic Rankine Cycles (ORCs) for the exploitation of low temperature heat sources. Specifically, the attention has been focused on low-enthalpy geothermal energy for small-scale applications. To this purpose a thermodynamic model has been developed and a parametric investigation has been performed considering different organic fluids (isobutane, isopentane, and R245ca). Saturated conditions at the expander inlet have been adopted and the effect of the internal regenerator on the system performances has been evaluated. The investigation highlights the large impact of the evaporation temperature on the ORC behaviour and the positive influence of the internal regenerator at the highest temperatures. Conversely, the effect of the internal heat exchanger reduces when the evaporation temperature decreases. Furthermore, a possible application in the Košice Basin (Slovakia) has been analysed. The investigation demonstrates that the organic Rankine cycle represents an interesting option for efficient valorisation of low-enthalpy geothermal resources and electricity production in small-scale applications. [ABSTRACT FROM AUTHOR]